Substrate Inhibition of Transglucosyl-Amylase by Maltose

Transglucosyl-amylase was inhibited by maltose when maltose served as a substrate. As a function of substrate concentration, the rates initially rose proportionately with increases of maltose levels until a maximal rate was attained. Further increases of maltose concentration decreased reaction rates. The attainment of a maximal rate with increasing substrate concentration and close correspondence between experimental and calculated rates indicated the involvement of ternary complex formation. Evidence also suggested that substrate inhibition is caused by maltose competing with water for the acceptor sites during complex formation.